A Novel Communication-Based Average Voltage Regulation Scheme for a Droop Controlled DC Microgrid

In a dc microgrid, enhanced voltage regulation (VR) and load sharing (LS) are necessary for the economic and reliable operation of the system. Traditionally, droop control is used for LS in microgrids. However, because of the nature of the droop control, good VR and accurate LS cannot be achieved simultaneously. To overcome this drawback, a low-bandwidth, communication- based average VR technique along with an algorithm for equal voltage correction factor is proposed in this paper. Here, precise LS is achieved via droop control using a high value of droop gain, while good VR is obtained through low-speed control area network (CAN) communication, which provides fault tolerance and expandability feature to the system. Only the local dc bus voltage information is exchanged over CAN by the grid connected converters, which ensure low communication traffic. Thus, sufficient bandwidth is available on the CAN bus that can be used for control and monitoring purpose-a highly desirable proposition for a smart grid application. Effect of communication delays on system stability has been modeled and analyzed. Simulation and experimental results are presented to validate the feasibility of the proposed scheme. Plug-n-play and fail-safe features of the proposed technique are highlighted.